Vaadin Dialog "steeling" Focus from Custom Javascript Component

I added a TinyMCE Javascript Editor (wysiwyg html editor), and it works fine in general.

But when i add it in a Vaadin Dialog it always loses Focus instantly because of something the dialog is doing.

I read that people experienced similar problems when adding tinymce in a Twitter Bootstrap modal dialog, but the same solutions did not apply to the vaadin-dialog.

Has anyone an idea how to approach this issue?